Types

• There are two main types of emulsions: macroemulsions and microemulsions. Macroemulsions are those with generally larger droplet sizes. They are characterized as being kinetically stable, meaning they are not likely to cause a chemical reaction. Microemulsions, on the other hand, are thermodynamically stable. They may cause a chemical reaction more naturally and are less likely to revert back to their original state if they do so. The droplet sizes in these are much smaller as well. Nanoemulsions are measured in nanometers and are used in situations where emulsions are required at very minute, microscopic levels.
  
  

Formation

• Some emulsions form through a natural and spontaneous chemical reaction, though more often than not they are created via mechanical means. Shaking is one way to make an emulsion. The physical jarring of molecules causes the formation of smaller and smaller droplets. A typical example of this is shaking up a bottle of salad dressing. However, shaking is inefficient as it does not create small enough droplets. Machines that can create greater agitation are used to produce more efficient emulsions. Added to emulsions are stabilizer agents that add a film to individual droplets, preventing the emulsion from separating into two liquids over time.
  
  

Uses

• Emulsions are used in a number of different ways. They are necessary in the manufacturing of synthetic rubber and plastics, for instance. They are also used in the dyeing and tanning industries. The cosmetics industry also uses emulsions to prepare shampoos, salves and various moisturizers. Medical products also require emulsions, like medicinal creams and topical ointments. Microemulsions are used in the delivery of vaccines, and firefighters use emulsions in the form of extinguishing foam.
  
  

Potential

• Studies involving emulsions are numerous and diverse. For instance, in 2011, Chinese chemists developed a device that enables researchers to create multicompartmental emulsions, where droplets are placed within droplets. This new system opens up research into the fields of template synthesis, synergistic delivery, microreactions and bioassay. Nano-sized, oil-based emulsions are also being tested in the hopes that they can be used to target and destroy cancerous tumors.